1. Field of the Invention
The invention relates to a circuit for processing an audio signal, comprising:                an input for receiving the audio signal and an output for supplying an output signal,        electing means coupled to the input for selecting a frequency band of the audio signal,        harmonics generator coupled to the selecting means for generating harmonics of the selected signal,        adding means coupled to the input as well as to the harmonics generator for supplying a sum of the input signal and the generated harmonics to the output.        
The invention also relates to an audio reproduction system comprising such a circuit.
The invention further relates to a method for processing an audio signal, comprising the steps of:                selecting a frequency band of the audio signal,        generating harmonics of the selected signal,        supplying a sum of the audio signal and the generated harmonics.        
2. Description of the Related Art
A circuit according to the preamble is known from European Patent Application EP-A 546 619. In the known circuit, a low frequency band of an input signal is selected and supplied to a harmonics generator for generating harmonics of the selected signal. In this way, low-frequency perception of the audio signal is improved upon. In the known circuit a full-wave rectifier is used as harmonics generator. A drawback of the full-wave rectifier is that it generates only even harmonics.